Limit is a basic concept in calculus, which refers to such a changing trend and the trend value (limit value) that variables gradually tend to be stable in a certain changing process.

The concept of limit was finally strictly expounded by Cauchy and Wilstrass. In modern mathematical analysis textbooks, almost all basic concepts (continuity, differentiation and integration) are based on the concept of limit.

Extended data:

There are many ways to find the limit:

1, continuous elementary function, to find the limit in the definition domain, you can directly substitute this point to get the limit value, because the limit value of continuous function is equal to the function value of this point.

2. Eliminate zero factor (for 0/0 type) by using unit deformation.

3. Use the relationship between infinity and infinitesimal to find the limit.

4. Find the limit by using the property of infinitesimal.

5. The original formula can be simplified and calculated by using equivalent infinitesimal replacement to find the limit.

6. Use two limit existence criteria to find the limit, and some topics can also be enlarged and reduced, and then use the pinch theorem to find the limit.